Bending Strength of a Horizontally Curved Composite I-Girder Bridge

Abstract

Horizontally curved I-girders are subjected to combined vertical bending and torsion under gravity loads alone. The torsional behavior of open I-shaped girders is commonly and conveniently transformed to self-equilibrating lateral bending of flanges. The interaction of vertical bending and lateral flange bending reduces the vertical moment–carrying capacity of the section. The interaction equations for predicting the nominal bending strength of horizontally curved I-girders of compact-flange sections subjected to vertical moment and torsion have been derived. Singly symmetric composite and noncomposite I-shaped cross sections in the positive and negative moment zones, respectively, are considered. These strength criteria are based purely on the static equilibrium of the cross section with no secondary amplification considered. The limitations and applicability of the derived equations toward the design use are demonstrated and analyzed.